The Use of Fetal Fibronectin to Predict Delivery Due to Abruptio Placenta

Optimal care of the pregnant trauma patient requires prompt and efficient care by a
multidisciplinary team to evaluate both maternal and fetal status. Approximately 7% of
pregnancies are complicated by trauma and traumatic injury remains the leading cause of
non-obstetric maternal death.1-3 In the case of major or life-threatening trauma in
pregnancy, assessment and stabilization of maternal cardiovascular and respiratory status is
paramount and management is generally dictated by standard adult advanced cardiovascular
support algorithms. In contrast, the evaluation and management of minor trauma in pregnancy
is variable and often provider dependent.4-7 Regardless of the clinical and laboratory
evaluation performed, the universal goal is to prevent maternal injury or death and optimize
pregnancy outcomes.

Maternal trauma has been associated with adverse pregnancy outcome, including preterm labor,
abruptio placenta, uterine rupture and fetal death.8, 9 Traditional trauma scoring systems
correlate well with the severity of maternal injury and are useful in triaging the mother;
however, these scoring systems have not been predictive of adverse pregnancy outcome.10,11
Major or life-threatening maternal trauma, which includes maternal shock, head injury
resulting in coma, and emergency laparotomy for maternal indications is associated with a
40-50% fetal loss rate as compared to 1-5% in pregnant women after minor trauma. The risk of
preterm labor after maternal trauma is increased 2-fold and the prevalence of abruptio
placenta after minor blunt abdominal trauma is reported at 8%. 3,6-9,12

Upon initial evaluation in the obstetrical triage setting, the examination of maternal trauma
patients is focused on detection of impending labor or abruptio placenta. This evaluation
includes detailed history of the accident, physical examination, abdominal and transvaginal
ultrasound to evaluate placental location and/or evidence of placental abruption and cervical
length, external uterine contraction monitoring, continuous fetal heart rate monitoring and
blood tests such as CBC, blood type, coagulation profile and Kleihauer-Betke staining.
Although much has been written on the subject of trauma during pregnancy, there is little
concrete data on objective measures which can be used to dictate triage and management
decisions. A recent study by Cahill et al.13 has advocated for review of the extensive
evaluations often performed after maternal trauma, specifically minor trauma, because they
determined that none of the commonly used clinical and laboratory measures are predictive of
adverse outcomes. Identification of laboratory measures predictive of impending delivery due
to placental abruption will potentially enable physicians to individualize triage and
evaluation of the maternal trauma patient, as well as direct treatment and management.

Fetal fibronectin is an extracellular matrix protein that is normally found in the fetal
membranes and decidua.14 It is essentially an adhesive glycoprotein or "glue" at the
maternal-fetal interface. In a normal pregnancy, fFN is undetectable in vaginal secretions
from weeks 22 to 35. Disruption of the maternal-fetal interface causes the release of fFN
into cervical and vaginal secretions. Detection of fFN before the normal onset of labor is an
indicator of preterm birth risk, allowing opportunity to provide appropriate intervention.
According to previous studies, the clinical utility of fFN lies in its negative predictive
value. In non-trauma patients, the sensitivity of fFN in predicting impending delivery
(within 7 days) is greater than 90%. A negative fFN result can be used to rule out impending
deliver with greater than 99% certainty.15

Because abruptio placenta secondary to maternal trauma is the result of shearing forces
separating the placenta from the uterine decidua, this outcome could potentially be predicted
by a positive fFN result. This study is therefore undertaken to determine if the presence of
fFN in cervicovaginal secretions is predictive of impending delivery or placental abruption
in patients with maternal trauma. With better knowledge of the probable outcomes following
maternal trauma and using the appropriate diagnostic and therapeutic modalities, optimal care
following minor maternal trauma for the pregnant patient and fetus can be provided.

Inclusion Criteria:

- Singleton intrauterine pregnancy ≥20 weeks and ≤35 weeks gestational age

- Chief complaint of minor maternal trauma including motor vehicle accident, patient
fall or assault with absence of maternal conditions outlined in exclusion criteria

Exclusion Criteria:

- Maternal shock

- Unstable vital signs

- Altered sensorium

- Head injury resulting in coma

- signs or symptoms of intraperitoneal bleeding

- Emergency laparotomy for fetal or maternal indications

- Bone fractures

- History of previous abruptio placenta

- Known or suspected placenta previa

- Rupture of membranes

- Multiple gestation

- Advanced cervical dilatation ≥3cm

- Non-reassuring fetal status requiring intervention

- Vaginal bleeding on presentation

- History of intercourse and/or digital vaginal exam and/or vaginal ultrasound ≤24 hours
prior to presentation

- Illicit drug use